I think that is an excellent question. I can only guess at the answer, based on what I've read over the years. I believe that there are various grades of steel both in the stainless and the carbon, and that the answer for accuracy, durability, etc. may vary more with the grade or type of steel than whether it is stainless or not. Based upon the use and demands required of the barrel (machinability, heat, military, cartridge intensity, etc.) the type of steel would vary in different guns and in some cases, either one or the other may have the advantage. In terms of off the shelf hunting rifles, I don't think I've ever heard of any practical difference in accuracy or longevity, but I'm just surmising on this subject.